1. Field of the Invention
The present invention relates to an optical mold for replicating or reproducing curved optical surfaces having the corresponding shape to that of a prototype and manufacturing methods therefor.
2. Description of the Prior Art
In reproducing curved optical surfaces having the corresponding shape to that of an optical prototype by conventional method, such curved surfaces are reproduced on glass base directly from an optical prototype. Speaking more concretely with reference to FIG. 1 attached hereto, a curved optical surface is reproduced by forming a layer of release agent 2 on the surface of an optical prototype 1, further forming a layer 3 of photopolymerizable bonding agent or resin, bringing a base 4 made of glass into contact with said layer 3, thereafter hardening said layer 3 of bonding agent or resin (hardening photopolymerizable material by irradiating it with rays) and then detaching said layer from said optical prototype 1 to obtain the resin layer 3 having the curved surface corresponding to that of said optical prototype on the surface of said glass base. However, such a conventional manufacturing method has drawbacks that said optical prototype is made of glass and is therefore easily cracked, and that delicate care is required to release a reproduced optical surface from the prototype since both of said prototype and base are made of glass materials which have little difference in their coefficients of expansion. In addition, it is necessary to prepare numerous optical prototypes for reproducing a large number of optical curved surfaces. However, it is never easy to prepare numerous optical prototypes, for example, having a non-spherical surface for reproducing optical elements having non-spherical optical surfaces. As is understood from the above descriptions, the conventional method for reproducing optical curved surfaces directly from an optical prototype is disadvantageous for mass production.